Stride-to-stride variability while backward counting among healthy young adults

BACKGROUND: Little information exists about the involvement of attention in the control of gait rhythmicity. Variability of both stride time and stride length is closely related to the control of the rhythmic stepping mechanism. We sought 1) to determine whether backward counting while walking could provoke significant gait changes in mean values and coefficients of variation of stride velocity, stride time and stride length among healthy young adults; and 2) to establish whether change in stride-to-stride variability could be related to dual-task related stride velocity change, attention, or both. METHODS: Mean values and coefficients of variation of stride velocity, stride time and stride length were recorded using the Physilog(®)-system, at a self-selected walking speed in 49 healthy young adults (mean age 24.1 ± 2.8 years, women 49%) while walking alone and walking with simultaneous backward counting. Performance on backward counting was evaluated by recording the number of figures counted while sitting alone and while walking. RESULTS: Compared with walking alone, a significant dual-task-related decrease was found for the mean values of stride velocity (p < 0.001), along with a small but significant increase for the mean values and coefficients of variation of stride time (p < 0.001 and p = 0.015, respectively). Stride length parameters did not change significantly between both walking conditions. Dual-task-related increase of coefficient of variation of stride time was explained by changing stride velocity and variability between subjects but not by backward counting. The number of figures counted while walking decreased significantly compared to backward counting alone. Further, the dual-task related decrease of the number of enumerated figures was significantly higher than the dual-task related decrease of stride velocity (p = 0.013). CONCLUSION: The observed performance-changes in gait and backward counting while dual tasking confirm that certain aspects of walking are attention-demanding in young adults. In the tested group of 49 young volunteers, dual tasking caused a small decrease in stride velocity and a slight increase in the stride-to-stride variability of stride time, while stride velocity variability was not affected by the attention-demanding task. The increase in stride time variability was apparently the result of a change in gait speed, but not a result of dual tasking. This suggests that young adults require minimal attention for the control of the rhythmic stepping mechanism while walking

Vitamin D deficiency and depression: Causal relationship or artifact?

International audienc

The Role of Vitamin D in Depression: From a Curious Idea to a Therapeutic Option

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Nutrient Biomarker Patterns, Cognitive Function, and Mri Measures of Brain Aging

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Vitamin D and white matter abnormalities in older adults: a cross-sectional neuroimaging study.

BACKGROUND AND PURPOSE: Morphological brain changes related to hypovitaminosis D have been poorly studied. In particular, the age-related decrease in vitamin D concentrations may explain the onset of white matter abnormalities (WMA) in older adults. Our objectives were (i) to investigate whether there was an association between serum 25-hydroxyvitamin D (25OHD) concentration and the grade of WMA in older adults and (ii) to determine whether the location of WMA was associated with 25OHD concentration. METHODS: One hundred and thirty-three Caucasian older community-dwellers with no clinical hydrocephalus (mean 71.6 ± 5.6 years; 43.6% female) received a blood test and a magnetic resonance imaging scan of the brain. The grades of total, periventricular and deep WMA were scored using semiquantitative visual rating scales from T2-weighted fluid-attenuated inversion recovery images. The association of WMA with as-measured and deseasonalized 25OHD concentrations was evaluated with the following covariates: age, gender, body mass index, use of anti-vascular drugs, number of comorbidities, impaired mobility, education level, Mini-Mental State Examination score, medial temporal lobe atrophy, serum concentrations of calcium, thyroid-stimulating hormone and vitamin B12, and estimated glomerular filtration rate. RESULTS: Both as-measured and deseasonalized serum 25OHD concentrations were found to be inversely associated with the grade of total WMA (adjusted β = -0.32, P = 0.027), specifically with periventricular WMA (adjusted β = -0.15, P = 0.009) but not with deep WMA (adjusted β = -0.12, P = 0.090). Similarly, participants with 25OHD concentration33% higher grade of periventricular WMA than those with 25OHD ≥75 nM (P = 0.024). No difference in average grade was found for deep WMA (P = 0.949). CONCLUSIONS: Lower serum 25OHD concentration was associated with higher grade of WMA, particularly periventricular WMA. These findings provide a scientific basis for vitamin D replacement trials

Mobile Geriatric Team and Length of Hospital Stay Among Older Inpatients: A Case-Control Pilot Study

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Higher gait variability is associated with decreased parietal gray matter volume among healthy older adults

The objectives of this study were to examine the association of stride time variability (STV) with gray and white matter volumes in healthy older adults, and to determine the specific location of any parenchymal loss associated with higher STV. A total of 71 participants (mean age 69.0 +/- 0.8 years; 59.7 % female) were included in this study. All participants had a 1.0 Tesla 3D T1-weighted MRI of the brain to measure gray and white matter volumes. STV was measured at steady-state self-selected walking speed using an electronic footswitch system. We found an association between higher STV and lower gray matter volume in the right parietal lobe (e.g., angular gyrus, Brodmann area 39, cluster corrected pFWE = 0.035). There were no significant associations between STV and higher gray matter volume or change in white matter volume. To the best of our knowledge this study is the first to identify a significant association of higher STV with lower right parietal gray matter volume in healthy older adults

Association Between Serum 25-Hydroxyvitamin D Concentration and Optic Chiasm Volume

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Vitamin D concentration and lateral cerebral ventricle volume in older adults

Scope Vitamin D deficiency is associated with an enlargement of the lateral cerebral ventricles in rodents. The effect of low serum 25-hydroxyvitamin D (25OHD) on lateral cerebral ventricle volume has not been studied yet in humans. The purpose of this cross-sectional study was to determine whether vitamin D deficiency was associated with greater lateral cerebral ventricle volume in older adults. Methods and results Ninety-two Caucasian community-dwellers with no clinical hydrocephalus (mean, 72.2 +/- 6.2 years; 46.7% female) were divided into two groups according to serum 25OHD concentration (deficiency &lt;= 50 nmol/L; normal &gt; 50 nmol/L). Cerebral ventricular volume was quantified using semi-automated software from three-dimensional T1-weighted MRI. Age, gender, body mass index, blood pressure, education level, Mini-Mental State Examination, white matter lesions, and serum calcium concentrations were used as covariates. There was an inverse linear association between 25OHD concentration and ventricular volume (p = 0.049). Compared to individuals with normal 25OHD, those with 25OHD deficiency (n = 33) had 28% larger lateral ventricles (46.9 +/- 26.8 mL versus 36.6 +/- 16.4 mL, p = 0.026). Vitamin D deficiency was associated with an increase in ventricular volume (adjusted beta = 16.55, p = 0.023). The ventricular enlargement involved ventricle bodies (p = 0.025) but not temporal horns (p = 0.112). Conclusion Serum 25OHD deficiency was associated with larger lateral cerebral ventricles. These findings provide a scientific base for vitamin D replacement trials

‘Faster counting while walking' as a predictor of falls in older adults

Objective: to establish whether changes in a spoken verbal task performance while walking compared with being at rest could predict falls among older adults. Design: prospective cohort study of 12 months' duration. Setting: twenty-seven senior housing facilities. Participants: sample of 187 subjects aged 75-100 (mean age 84.8±5.2). During enrollment, participants were asked to count aloud backward from 50, both at rest and while walking and were divided into two groups according to their counting performance. Information on incident falls during the follow-up year was monthly collected. Measurements: the number of enumerated figures while sitting on a chair and while walking, and the first fall that occurred during the follow up year. Results: the number of enumerated figures under dual-task as compared to single task increased among 31.5% of the tested subjects (n=59) and was associated with lower scores in MMSE (P=0.034), and higher scores in Geriatric Depression Scale (P=0.007) and Timed Up & Go (P=0.005). During the 12 months follow-up, 54 subjects (28.9%) fell. After adjusting for these variables, the increase in counting performance was significantly associated with falls (adjusted OR = 53.3, P < 0.0001). Kaplan-Meier distributions of falls differed significantly between subjects who either increased or decreased their counting performance (P < 0.0001). Conclusions: faster counting while walking was strongly associated with falls, suggesting that better performance in an additional verbal counting task while walking might represent a new way to predict falls among older adult